Wheelchairs having adjustable component parts are known and an example thereof is described and illustrated in U.S. Pat. No. 5,593,211. It is also known to extend the seat portion of a chair having an extendable cushion thereon, such as described in U.S. Pat. Nos. 5,588,708 and 6,454,353. However, these adjustable features only apply to few component parts of a chair or a wheelchair and usually such chairs are custom fit for an intended user and this is particularly so with wheelchairs for handicapped persons.
When constructing a wheelchair for a handicapped person, such as a paraplegic person, it is customary to create a mold of a portion of that person's body and construct a chair with molded parts and adjustable pads to fit that particular person. This is a costly procedure. Further, if that person is of a younger age and is still growing, then that chair becomes uncomfortable to the person as his body dimensions change and it is then required to reconstruct parts of the chair. Because of the high cost of constructing these chairs often handicapped persons are fitted with chairs of inferior quality and the result is that they can lead a very uncomfortable life.
There is also a need to provide a chair or sofa wherein the seat portion may be automatically adjusted to suit an intended user for a short period of time to make the user comfortable. The backrest may also be adjusted in a similar manner and each time the user changes, the seat and backrest are modified. This can be done by the intended user or automatically if the size parameters of the user is known.
There is a further need to provide an adjustable support base assembly for wheelchairs wherein the position of the chair can be modified depending on the intended user while maintaining the same wheels or providing only a few wheel sizes whilst maintaining the center of gravity along the axle of the main wheels.